Field of the Invention
The present invention relates to a power converter and a power converter for a railroad vehicle, and more particularly, it relates to a power converter and a power converter for a railroad vehicle, both of which include a plurality of semiconductor element groups each including a plurality of semiconductor switching elements.
of Description the Background Art
A power converter and a power converter for a railroad vehicle, both of which include a plurality of semiconductor element groups each including a plurality of semiconductor switching elements is known in general, as disclosed in Japanese Patent Laid-Open No. 2007-104784.
A power converter disclosed in Japanese Patent Laid-Open No. 2007-104784 includes a power converter for a vehicle. This power converter includes a heat receiving block. On a semiconductor element mounting surface of the heat receiving block on one side, semiconductor element groups of a plurality of phases are provided. Furthermore, on a non-semiconductor element mounting surface of the heat receiving block on the other side, a heat radiator that radiates the heat of the semiconductor element groups is provided. The heat radiator includes a plurality of plate-shaped fins arrayed along the crosstie direction of the vehicle.
The semiconductor element groups of the plurality of phases are disposed side by side in the crosstie direction of the vehicle. Each of the semiconductor element groups of the plurality of phases includes four semiconductor elements Q1 to Q4 and two diode elements. Specifically, in each of the semiconductor element groups of the plurality of phases, the semiconductor element Q1, the semiconductor element Q2, the semiconductor element Q3, and the semiconductor element Q4 are connected in series in this order from the positive voltage side. Furthermore, the four semiconductor elements and the two diode elements are linearly aligned in a vehicle traveling direction. That is, the fins with which the four semiconductor elements Q1 to Q4 and the two diode elements overlap in a plan view are common to each other (the same as each other).
Here, a converter has a time during which the element loss is large, longer than that of an inverter. Among the four semiconductor elements Q1 to Q4, the semiconductor elements Q2 and Q3 that are frequently switched generate a larger amount of heat than the other elements. Therefore, in the power converter disclosed in Japanese Patent Laid-Open No. 2007-104784, heat of both the semiconductor element Q2 and the semiconductor element Q3 that generate a relatively large amount of heat is radiated by only the common fins, and thus the heat of the semiconductor element Q2 and the semiconductor element Q3 is not sufficiently radiated such that the temperatures of the semiconductor element Q2 and the semiconductor element Q3 are disadvantageously increased. Thus, the power converter may fail due to insufficient heat radiation.